The invention has a particular application to the production of aluminum oxide in an electric arc furnace. In such a process, abrasive grade bauxite is mixed with a coke reductant and iron in the form of chips, cast iron bits, or iron pellets, and then subjected to the intense heat of electrical discharges between massive electrodes. Aluminum oxide is poured periodically from the furnace into a refractory-lined steel vessel and allowed to cool. During the melting process, ferrosilicon materials are precipitated, and because of their density are trapped beneath a liquid aluminum oxide layer produced in the process. Relatively clean aluminum oxide will be poured at predetermined intervals, until at some point, because of the accumulation of ferrosilicon materials at the bottom of the furnace, it becomes difficult to pour the aluminum oxide without visible contamination by the precipitated materials. The precipitated materials must then be poured from the furnace. Pouring of the precipitated materials is a particularly dangerous process, because the materials are heated to a temperature in excess of about 2100.degree. C. which is well above their melting point, and the materials are consequently very fluid and intensely hot.
According to present practice, the precipitated materials are poured into deep, refractory-lined steel shells, such as the shells used to contain the aluminum oxide when poured. Because of the insulating property of the refractory linings, a cooling period in the order of 2-3 days is not uncommon before the materials are sufficiently solidified to permit removal. Such an extended cooling time increases the risk of burn-through of the refractory lining, and the attendant risk of spillage. The consequences of spillage are so severe that it is not uncommon for the cooling vessel to be allowed to stand for a period of several hours to permit a thin film to form over the surface of the super-heated materials thereby reducing the possibility of minor spillage with movement of the cooling vessel to a more convenient cooling location.
Another removal process involves pouring the super-heated materials into a spillway leading to a fixed bin or pit. The spillway is generally lined with refractory brick, and the pit or fixed bin lined with a similar refractory material which is then covered with layers of a granular refractory such as ordinary silica sand. The process has the advantage that the intensely heated materials are very quickly removed from the melting area to a safe location; however, the process requires periodic maintenance to the refractory lining of the spillway, and the subsequent disposal of cooled materials can be relatively inconvenient.
The development of a better method of disposing of these super-heated materials has been hindered because of the relative reluctance to experiment in this area. The danger of spillage and the intense heat of the materials represent a very substantial risk to plant and personnel which militates against experimentation. However, the inventors have developed and tested a novel cooling car for removing such super-heated materials from a melting furnace, which car permits a considerable reduction in cooling time, and also permits convenient disposal of solidified materials.